"Email this user" was broken Aug 14 to 9am Aug 16. If you sent someone a message in this period, please send it again.

1,2

Table of n, a(n) for n=1..65.

Index entries for linear recurrences with constant coefficients, signature (0,2,0,-1).

a(n)=(1/4)*(11*n+9*n*(-1)^n+1+(-1)^(n-1)). [Paolo P. Lava, Apr 16 2010]

G.f.: x*(1+10*x) / ( (x-1)^2*(1+x)^2 ). - R. J. Mathar, Jun 18 2014

Cf. A008592, A101233.

Sequence in context: A005483 A228276 A040099 * A086068 A262557 A030595

Adjacent sequences: A173234 A173235 A173236 * A173238 A173239 A173240

nonn,easy

Mark Dols, Feb 13 2010

approved